Baltimore Mayor Stephanie Rawlings-Blake. (Kim Hairston/Associated Press)

SINCE TAKING office in 2010, Baltimore Mayor Stephanie Rawlings-Blake (D) has nudged, coaxed and pushed for reforms in her city’s police department; at best, she’s had partial success. This week she went much further, formally asking the Justice Department to launch a full-scale inquiry into what many Baltimoreans have long regarded as a pattern of harassment, excessive force and bogus and unlawful arrest by the police, especially in black neighborhoods.

The mayor’s hand may have been forced by the public outrage, violence and political outcry that followed the death of Freddie Gray, the young African American who sustained a lethal injury while in police custody last month. Still, her request — for just the sort of massive federal intervention that many mayors resist — is a brave and timely move. It would be surprising if Attorney General Loretta Lynch, who met with politicians, police and community leaders in the city on Tuesday, declined.

Federal civil rights probes of other big-city law enforcement agencies have often resulted in consent decrees that compel police to undertake rigorous and sometimes onerous reforms and abide by years of court monitoring. Given what’s been widely reported before and since Mr. Gray’s death, those sorts of draconian steps may well be warranted in Baltimore’s case to repair what Ms. Rawlings-Blake called the “fractured relationship between the police and the community.”

They may also be required to fix the actual problems with the police that the mayor herself has long acknowledged and tried on her own to address.

Her steps have included recruiting new and reform-minded leadership for the department; encouraging the abolition of a notorious police unit known as the Violent Crimes Impact Section, which was a lightning rod for community complaints; and, last fall, launching an ambitious plan to combat police brutality that included expanding the department’s internal affairs division, which investigates allegations of officers’ misconduct. She has also pushed to redraw rules enshrined in the police union contract, which sometimes impede efforts to discipline bad cops.

More recently, Ms. Rawlings-Blake has promised to launch a program to equip patrol officers with body cameras before the end of this year. The cameras are widely thought to be effective in promoting more civil interactions between cops and civilians and deterring police abuse.

By temperament, the mayor is a cautious politician, wary of alienating the police rank-and-file. She previously green-lighted a “collaborative review” of the police by the Justice Department — a process, still underway, that is likely to result in recommendations for reform but not court orders. She has cited statistical evidence, including a sharp drop last year in complaints of police brutality, which suggests her push for progress is bearing fruit. Nonetheless, in the aftermath of Mr. Gray’s death, she asked the Justice Department to review the circumstances of his arrest and injuries.

Now, by her appeal for federal intervention, Ms. Rawlings-Blake has shown she is also capable of bold steps to tackle head-on what has been a toxic undercurrent in Baltimore’s civic life for too long.